twice the square root of a number increased by 5 is 23 The phrase a number means an arbitrary variable, let's call it x: x The square root of a number means we raise x to the 1/2 power: sqrt(x) the square root of a number increased by 5 means we add 5 to sqrt(x): sqrt(x) + 5 twice the square root of a number increased by 5 means we multiply sqrt(x) + 5 by 2: 2(sqrt(x) + 5) The phrase is 23 means we set 2(sqrt(x) + 5) equal to 23: 2(sqrt(x) + 5) = 23